For molding and curing green tires, presses are known to be employed comprising a fixed bed designed to receive, on top, at least a bottom mold for a green tire, and having two substantially vertical, lateral uprights, on each of which there is formed a substantially vertical slot open at the top. The said two slots define the slideways of a crossbar constituting a common slide for two crank mechanisms, each connected to one of the said uprights. The connecting rod of each of the said crank mechanisms is of such a length that the said slide moves over the top end of the said slots when the connecting rods reach the top dead center position.
The said slide supports, in rotary manner, a crosspiece located between the said two uprights and fitted with at least a top mold for a green tire. The said crosspiece is connected integral with two appendixes (sliding shoes), the free end of each of which engages a substantially vertical guide formed on a respective upright and arranged in such a manner that its top end is reached by its respective appendix after the said slide reaches the top end of the respective said guides, and before the connecting rods of the said two crank mechanisms reach the top dead center position.
Clearly, therefore, when the crosspiece on the press is pushed up by the two crank mechanisms for opening the mold, the crosspiece is moved upwards until the said two appendixes reach the top end of the respective guides. Further rotation of the cranks, beyond this point, causes the slide to slide backwards along supports formed on top of the uprights, and, at the same time, tilts the crosspiece back about the slide axis. As a result, the mold on the crosspiece turns upwards, thus enabling full access for removing the molded tire. Such backward tilting of the crosspiece occurs as soon as the slide moves over the top of the uprights, and is caused by the tiltback torque produced by the combined effect of the slide sliding backwards by gravity along the said supports formed on top of the uprights, and the said appendixes on the crosspiece engaging inside the respective guides.
Though widely used for molding tires, presses of the aforementioned type involve a number of both functional and structural drawbacks. Tilting back the crosspiece on the press for enabling access to and removing the molded tire(s) is not only a relatively time-consuming operation, which consequently slows down production, but also subjects the press itself to tiltback moments directly proportional to the weight of the molds involved. These moments, which are caused by rearward displacement of the center of gravity of the crosspiece in relation to the bed, are grounded through the bolts anchoring the bed to the floor, with the result that the bolts must be continually inspected and have a relatively short working life. The aim of the present invention is to provide a tire molding press involving none of the aforementioned drawbacks.